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My Machine

Posted: Tue Nov 20, 2012 5:40 pm
by edwardrford
As many people have noticed, my machine looks different almost every time I release a new video. I wanted to start a habit of posting an entry each time a variation of my current machine is displayed. Here's a video I shot last weekend of my current R&D machine in action. I'll apologize for the corny video in advance, it was my first time using iMovie :-)

(regarding the video: the toolpaths were not optimized. I only wanted to do 1 tool change, so I did all the logos in one operation. From there, I should have cut out each stand individually instead of jumping back and forth between the 4 of them...). All total I think the job took about 50 minutes start to finish. When the stands were done, I used a scrap piece of 100 grit sandpaper to finish the edges. The material being cut is 7/8" thick walnut. [it's really beautiful wood!]

Here's a rundown on what's different:

1.) The open front/back system has been in testing for several months now. The impetus behind the design exploration was finding a simple way to scale the machine in the X axis direction. By default, scaling in the Y was very easy. To date, it's working very well. The machine seen in this video uses the standard Y axis rails (375mm) and the X axis rail is a piece of 1m makerslide cut down to about 600mm

2.) Dual Y axis drives - a must for a gantry that is this wide

3.) Clamping system - As you can see there are two t-tracks running up the side of the machine and another running horizontally across the middle of the machine. Those tracks combined with the t-bolts that slide into them give a very simple and effective method of clamping material to the work surface. As you can also see, my actual "clamps" as just a few extra straps I had laying around. The proper clamp to use with these tracks look like this:
hold_down_clamp.jpg (7.28 KiB) Viewed 5738 times
In retrospect i should have put that third rail (the one running horizontally) right in the middle of the work area (countersunk). There have been several times when I wanted to machine something small and couldn't reach it with a clamp from the opposite side. I'll be changing that soon.

4.) Spindle - this is actually just a flexible hand piece from aliexpress I had really high hopes for this little thing, but in the end it's basically less powerful than a dremel and makes about the same amount of noise. I like it's size, but otherwise I'm not impressed. You can get the same thing but with a handpiece that will accept 1/4" bits, but given it's underpowered-ness (if that's a word?) I would saying actually using 1/4" bit for machining wouldn't be in the cards.

I'm still running this with my original buildlog 4-axis open source controller and using EMC2 to operate it.

So... what do you think? Anything in there look interesting?


Re: My Machine

Posted: Tue Nov 20, 2012 7:06 pm
by dointhangs
I am recently finding all of the bed stuff interesting as I spend frustrating moments with that, excited to run a job and then there are all kinds of ways just mounting stuff can go wrong.
My bed has t slot extrusion around the edges and then a couple of misc pieces that I can slide +x and -x in the middle of the bed. (its misumi 20-40).
I cant just buy the following clamp though as I think it wont fit in that misumi slot - its a bigger nut/screw diameter?
So I have to buy their t-slot too?
If so I want to think about a way to mate a clamp knob to a 5mm screw and get er done. Or?
Also have you ever seen any bed with a base as a sheet of a nice grid of tapped holes that one can mount a piece of extrusion to using brackets? then the hold down clamps mounted to the t slot. As you say this could be great for smaller pieces, to move the t-tracks towards the middle in the y axis as well as the x... Somebody has to sell stuff like that, maybe aluminum or something? Love the video, hey you got a good lawyer? I heard apple copyright lawyers are pretty good at what they do lol

Re: My Machine

Posted: Wed Nov 21, 2012 3:22 am
by edwardrford
Frank that's an amazing idea! I had totally forgotten about the captive nut method of holding things down.

It just so happened that I had a handful (maybe 5 or 6) of those types of nuts in my spare parts bin. I didn't know what I would do with them, but I couldn't bring myself to throw them away :-) Good thing, because they're exactly what we need to make this work!
t-nut_test.JPG (126.28 KiB) Viewed 5674 times
Here's the idea, for anyone who is unfamiliar:

You use something like this (called a captive insert nut or wooden t-nuts or knock-ins) in the table itself:
tnut_stock_image.jpg (7.29 KiB) Viewed 5674 times
Resulting in a table that looks like this:
tnut_table.png (739.77 KiB) Viewed 5674 times
So, here's my thought on how to make this happen:

You would need the following:
- 1 x Piece of MDF that is 12" x 12" and either 1/2" or 3/4" thick
- about 10 t-nuts (1/4"-20 thread size seems like a good size for this application)
- Some 1/4" screws in a few different lengths. You could also get fancy and add some Press-Fit Plastic Thumb Screw Heads for easy turning!
- Gorilla Glue (or any wood glue)

My estimation is this project would only cost about $20. Plus, you'd be making most of it on your machine!

Step 1: Take the piece of 12" x 12" MDF and place it into your shapeoko. You'll need to figure out a way to hold it down temporarily (we're not gluing it yet!). Double sized tape would probalby work
Step 2: I'll create a job file that uses a 1/8" end mill. The job will create a series of holes large enough to fit the intsertion nuts. In order to make the bottom of the nuts flush with the bottom of the MDF, a pocket will need to be created around the hole. This pocket operation will be part of the packaged job.
Step 3: Run the job, and half of your board will be overed with countersunk holes!
Step 4: Unfasten your MDF and flip it around (turn it 180 so your new countersunk holes are behind the gantry)
Step 5: Re-run the job
Step 6: Remove the 12" x 12" piece of MDF.
Step 7: Insert the t-nuts. They are called knock-ins because your have to bang the prongs into the wood with a hammer. We've pocked the holes so these will now be flush!
Step 8: Lightly sand (just scuff up) your wasteboard that came with the kit. Lighly sand the bottom of the MDF piece
Step 9: Wipe the dust/debris from both pieces.
Step 10: Apply a very small amount of water to a rag, rub the rag onto the wastboard that came with your kit (water helps the gorilla glue bond MDF together)
Step 10: Apply a liberal amount of gorilla glue to your 12" x 12" piece of MDF.
Step 11: Place your 12" x 12" piece of MDf onto your wasteboard that came with the kit.
Step 12: Put something heavy (like a dumb bell or a car) on top of the two pieces. Let them sit overnight.
Step 13: Come back to your machine the next day and marvel at what you've accomplished!
Step 14: We can design some hold downs that can be cut on the shapeoko.

So... what do we think? Am I the only one that thinks Frank might have solved one of the most frustrating parts of running the machine?


Re: My Machine

Posted: Wed Nov 21, 2012 7:29 am
by dointhangs
haha nice! Yes I am very happy to solve these problems for you :-)
You have me looking at these captive nuts p/n 99437A155 on
Somebody should do it, mount those underneath a sheet of drilled out aluminum, take pics - I love your mdf method but that could look pretty sweet as an aluminum sheet under there, right? (I loaded a shopping cart but my hand got shaky all of a sudden sorry. Maybe later though).
I found I had some of that aluminum strap around too. I need to dial it in but this method will totally work for small little pieces I have been messing around with like this, thanks for that idea too.
Screen shot 2012-11-20 at 11.13.13 PM.png
Screen shot 2012-11-20 at 11.13.13 PM.png (456.94 KiB) Viewed 5659 times